This question will remain open perpetually until its resolution unless China, Taiwan or the US stop existing.
This question will resolve after the conflict between China and Taiwan ends. If there is still fighting on the island after multiple years and the US intervenes much later in the war, this still resolves YES.
Direct intervention requires US forces engaging Chinese ones, this can include and is not limited to: Engaging Chinese naval assets, deploying boots on the ground in Taiwan, missile strikes on Chinese military bases, etc.
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@RemNi seems like creator might have gone inactive.
From a common sense perspective, no-one thinks the US would intervene in that scenario, and no-one who works on these things would interpret this question like that.
From the description, Taiwan would very likely continue to exist if it lost those islands and so this question would not resolve NO.
@JoshuaWilkes How does this question resolve if China takes the outlying islands and the US does intervene?
Ha
I think applying common sense to what I've said above it wouldn't resolve.
However,
If I had written this question I would have asymmetric resolution so it wouldn't resolve NO if they didn't but would resolve YES if they did.
@JoshuaWilkes right, N/A makes sense
Maybe a more active trader should re-write this question with a clearer description. It's not a bad question at face value.
@RemNi My apologies for the late response, my intention for this question was specifically about an invasion of the main Taiwanese island. An occupation of, say, Kinmen, by the PRC would not cause this question to resolve in either direction.
My specific criterion for a YES resolution is US forces intentionally firing on Chinese ones after being ordered to do so during an invasion of the island.
My specific criterion for a NO resolution is the PRC completely occupying the island after a successful invasion with no US forces ever having fired on Chinese ones.
I hope this removes some of the ambiguity from the question.